Energy Model Input Translator
Contents
1. Exhaust Fan Power Enter portion of exhaust fan power located in EER ARI Conditions Enter EER ARI conditions E Enter 6 ARI conditions Typical value is 350 CFM Q ARI Conditions CFM ton i Internal static pressure of unit at ARI CFM in H20 Internal Static ARI 1 00 Do not include filters Typical value is 1 00 i Enter combined fan and motor efficiency Typical Fan efficiency ARI 0 65 value is 0 65 Heating COP 32 Enter heating COP If using HSPF COP 0 27787HSPF 0 9667 Cancel OK Figure 2 Proposed system input form The user must enter a name and then must check off all options that apply As the options are checked off further inputs will appear as necessary The only inputs required regardless of options are supply fan power and airflow 4 4 1 Fan Power Calculations The fan power calculations are fairly straightforward The user enters the fan power kW and airflow CFM for each fan category supply return and exhaust and the spreadsheet calculates the kW CFM This calculation is not difficult but sometimes determining the fan power can be a challenge so a fan power calculator has been included This calculator takes the CFM total static pressure fan and motor efficiencies and calculates fan power in kilowatts This calculator is accessed by clicking the button located in the lower right hand corner of the form Energy Model Input Pre Processor User s Guide2. DA po Each component is described in detail below 4 1 LIGHTING POWER amp OCCUPANT DENSITY CALCULATOR The lighting power and occupant density calculator takes information about energy model thermal zone space types and determines baseline values lighting power density receptacle power density occupant density and occupant heat gain The baseline values are taken from ASHRAE 90 1 2007 and the 2005 California ACM Manual Title 24 Intent The intent of the manager is to automatically determine and organize baseline values based on a mix of space types for the following categories Lighting Power Density Receptacle Power Density Occupant Density e Occupant Heat Gain This tool can help energy modelers organize and compare large amounts of information on internal gains Early in the design conceptual energy models often include large zones which are a mix of a few space types this tool allows a weighted average of internal gains to be determined and documented for future review and revision While some energy modeling wizards allow for similar weighted averages to be created they do not account for occupancy sensor credits or document the percentage breakdown of space types for future revision Directions To begin click the Add Zone button and the following form appears Energy Model Input Pre Processor User s Guide 5 Zone Information Directions Enter information for thermal zone below Select zone sp
3. 21 4 6 1 eQuest Schedule Output isses sienne einn ntn enne nennt snnt en rentas 21 4 62 EnergyPlus Schedule Output esses eise sitne nnns innate ennt 22 MEL LO e E Tett 22 Energy Model Input Pre Processor User s Guide 3 3 OVERVIEW This software tool is a compilation of spreadsheet based calculators that were developed in response to the building energy modeling community s need for tools that translate design data and code requirements into typical energy modelinputs The goal in developing this tool is to reduce the time it takes to produce a quality energy model and therefore increase the use and accuracy of energy modeling in building analysis and design 3 1 COMPATIBILITY AND SAVING THEFILE The tool was developed in Microsoft Windows XP SP3 using Office 2007 The file has been saved down to Excel 97 2003 compatibility to provide greater usability efforts have been made to avoid compatibility errors but because the program uses sub routines problems may occur due to library locations These problems occur when Excel is updated and the path of a VBA library is changed This can be fixed by correcting the path by going to the VBA editor Alt F11 choosing Tools References selecting the library which has been modified and browsing to find the correct path Additionally when using Excel 2007 the workbook must continue to be saved as 97 2003 compatible xls as opposed to
4. a 2007 version xlsx 3 2 OTHER TOOLSAND MATERIALS This tool was developed by Rocky Mountain Institute RMI in conjunction with several other software tools and educational materials with the same goal in mind This includes e Model Manager A DOE 2 2 based Excel tool which streamlines parametric runs in DOE 2 2 based modeling software e LCCAid A tool for life cycle cost analysis made specifically for architects and building systems engineers Elements A freely available comprehensive integrated weather tool suitable for solving all of the common weather tasks associated with building energy modeling Features include read write convert between all major weather file formats and custom data visualization and analysis data editing and error checking Energy Audit Sample Forms Sample forms to assist building energy auditors in collecting the data required to complete comprehensive energy and financial analyses of proposed modifications to a building EMIT and other tools and content can be found at http ww w rmi org rmi ModelingTools Energy Model Input Pre Processor User s Guide 4 4 TOOL COMPONENTS EMIT is made up of six separate components Lighting Power amp Occupant Density Calculator Domestic Hot Water Calculator Cooling Tower Fan Efficiency Calculator Proposed System Fan Power amp Efficiency Calculator Baseline System Fan Power amp Efficiency Calculator Schedule Creator and Exporter Sv UA A
5. efficiency Table 1 Thermal Efficiency by Fuel Type Fuel Type Standard High Efficiency Efficiency Electric 0 98 0 98 Natural Gas 0 80 0 95 Oil 0 78 0 93 4 3 CooLING TOWER FAN EFFICIENCY CALCULATOR Intent The purpose of this spreadsheet calculator is to determine the proposed and ASHRAE 90 1 2007 baseline cooling tower fan efficiency and express that efficiency in various ways that may be required by energy modeling programs Energy Model Input Pre Processor User s Guide 10 4 3 1 Proposed Case The proposed case requires the user to input the type of fan axial or centrifugal nameplate horsepower condenser water flow and condenser water temperature difference The calculations assume ideal condenser water properties of 8 33 Btu gal F and that the full nameplate horsepower is equal to the brake horsepower This assumption is not ideal but ASHRAE 90 1 2007 does not differentiate nameplate from brake horsepower for cooling towers 4 3 2 Baseline Case The baseline case is based on ASHRAE 90 1 2007 Table 6 8 1G The only required input for the baseline case is condenser water flow rate as ASHRAE 90 1 2007 specifies that the baseline cooling tower will have an axial fan The same assumptions are made as in the proposed case and the COP of the baseline is calculated The COP is not actually dependent on the condenser flow rate but the calculations are shown for informational purposes 4 4 PRO
6. of the values is created and referenced by the IDF file To copy the created schedule to the simulation file the user should open both the created IDF file and the simulation IDF file in the IDF Editor In the schedule file scroll down to the Schedule File object in the Class List window Select the created schedule and click the Copy Obj button Move to the simulation file and go to the Schedule File class Click the Paste Obj button and the created schedule will become part of the simulation file 5 REFERENCES ASHRAE 90 1 2007 ASHRAE 90 1 2007 User s Manual ASHRAE Handbook HVAC Applications California 2005 ACM Manual Energy Model Input Pre Processor User s Guide 22
7. 00 in H2O This value is estimated from manufacturers data on many different packaged RTUs The ASHRAE 90 1 committee may decide to stipulate a specific allowable internal static value for baseline systems in the future which would obviously supersede this value One alternate solution to using the method outlined above would be for ASHRAE 90 1 to set a baseline allowable fan heat for example at 396 of rated capacity In this case we could use equation 22 to directly calculate COP 30 Qi rated F Q fan rated 1 03 Qi rated 1 03 3 413 3 413 3 413 FER Qtratea Q fan rated FER Qtratea 0 03 Qi rated EER 0 03 COP The above equation is fairly accurate relative to the complex calculations required otherwise Assuming an internal static of 1 00 in H2O the difference is between 0 6 to 13 8906 4 6 SCHEDULE CREATOR AND EXPORTER Intent Energy modelers often need to manipulate or deal with fractional schedule data outside of energy model programs Translating this data into energy model schedules can be extremely time consuming especially when dealing with 8760 data points This schedule creator and exporter produces eQuest input files inp or EnergyPlus input data files idf containing code language for modeling schedules Directions To begin click Create Schedule and select the appropriate modeling program A form then appears where the user can define the type of schedule to be created At the moment only Ann
8. 12 It is critical to assign the fan power and CFM for the proposed system appropriately The following definitions serve as a guide for this purpose Supply Fan Power Includes supply fan power for main air handlers or rooftop units as well as any dedicated outside air systems DOAS Do NOT include fan powered boxes no matter what their configuration is Return Fan Power Includes both return fans which have the same schedule as supply fans and relief fans which run only during economizer mode to relieve the building of excess pressure due to increased outside air quantities Exhaust Fan Power Includes all fans that exhaust building air to the outdoors 4 4 2 Compressor COP Calculation If the user clicks DX Cooling as a system option several input boxes appear because the most complicated calculation for the proposed system is compressor COP The method for calculating this value is taken from ASHRAE 90 1 2007 User s Manual equations G A through G C These equations relate EER to COP and are as follows 8 Total Input Power W Total Input Power W 9 COP Gross Cooling Capacity 2 i Compressor Power Condenser Fan Power W x 3 413 224 10 Gross Cooling Capacity 2 COP g Capacity 5 Total Input Power Supply Fan Power W x 3 413 8 W h Note that all values are at AHRI rated conditions Do not use actual design conditions because COP inputs to energy models generally are at rated cond
9. EMIT Energy Model Input Translator User s Guide gt ROCKY MOUNTAIN saw INSTITUTE 1820 Folsom Street Boulder CO 80302 303 245 1003 www rmi org May 2011 1 ACKNOWLEDGEMENTS The Energy Model Input Translator was developed with funding from Rocky Mountain Institute s Commercial Building Retrofit Initiative The following staff at Rocky Mountain Institute were involved in its development Aaron Buys Lead Developer Kendra Tupper Project Manager Ellen Franconi Content Support Additional thanks to International Building Performance Simulation Association IBPSA Gail Hampsmire GBCI Fred Porter Architectural Energy Corporation other beta testers in the energy modeling community Copyright 2010 2011 Rocky Mountain Institute Energy Model Input Pre Processor User s Guide 2 2 TABLEOF CONTENTS 1 2 2 TABLE OP TENTS ccntsissswmncsscssnccususunnsunnesecsnpacunudssunansupisapasnsisunniusdsunndacusunmsusidins 3 edic e 4 3 1 COMPATIBILITY AND SAVING nnn nnne rennen 4 3 2 OTHER TOOLSAND MATERIALS 4 JTOOLCOMPONERNUES ae di
10. POSED SYSTEV FAN POWER amp EFFICIENCY CALCULATOR Intent The proposed system calculator determines fan power for supply return and exhaust fans and it calculates compressor coefficient of performance COP and energy input ratio EIR Many of the user inputs for the proposed system inform the calculations for the baseline fan power on the subsequent tab Though this information transfer is not automatic The user must manually input these values in the baseline system tab Additionally this calculator helps a user break out fan power and compressor efficiency for their proposed packaged units The spreadsheet uses forms for data input Energy Model Input Pre Processor User s Guide 11 Directions To begin click Add System and the following form appears Proposed System Inputs Pi System System Name System Name System Notes Notes DX Cooling System Options Heat Pump Check all that apply V Misc Supply Fans Return Fan Exhaust Fan Nominal Cooling Capacity 240000 Enter nominal cooling capacity Supply Fan Airflow 8000 Enter design supply fan CFM Main Supply Fan Power 4 00 Enter supply fan power from fan located at unit Pow Enter power from any supplemental supply fans Misc Supply Fan 0 50 Do not include fan powered boxes Return Fan Airflow Enter design return fan CFM Return Fan Power Enter return fan power Exhaust Fan Airflow Enter portion of design exhaust fan CFM located in zone
11. Qi rated x SP rated Q _ SP rated i EER 55 615 in H20 trated 55 615 in H50 and 0 drops out to give us 26 SP rated eis 1 55 615 in H 0 3413 0 EER 55 615 in H0 If we define an arbitrary term X as follows then the equation will be easier to read 27 x SP rated 55 615 in H20 Substituting X in equation 26 we get 28 14 X CO Pyaseline 3 413 _y EER nin 9031 Energy input ratio EIR is the inverse of COP Going back to equation 27 SP ratea is the total static pressure drop through the system at rated conditions which we know from equation 14 is the sum of the internal and external static pressure drops so when combined with equation 27 we get 29 x SPinternal rated ST external rated 55 615 in H20 where SP external rated The minimum external static pressure specified in ANSI AHRI Standard 340 360 for the rated capacity of the baseline system as shown in Table 1 SPinternal rated The internal static pressure at rated conditions Energy Model Input Pre Processor User s Guide 20 However internal static is not governed by any standard so it should be assumed that internal static of the baseline system is equal to the internal static of the proposed system if there is a proposed system that corresponds to the baseline system If there is no corresponding proposed system or the internal static of the proposed system is unknown use the default value of 1
12. ace type s and enter percentage for each space type ASHRAE 90 1 2007 baseline values for lighting power density and 2005 California ACM Manual receptacle power density and occupant density and heat gain will be calculated for the zone Zone Name Zone Name Notes Notes Space Type Space 1 Atrium Floors 1 3 Space 2 None Space 3 None Space 4 None Proposed System Values Directions Enter values for lighting and receptacle power density for the proposed system or check the box to use baseline values Lighting Power Density 0 W sqft Use Baseline Value Lighting Occupancy Sensor No Yes Receptacle Power Density 0 W sqft Use Baseline Value Cancel OK Figure 1 Lighting receptacle and occupant density calculator input form Enter the zone name and any notes Select the zone space type s and enter the percentage of the zone taken up by that space type Multiple space types are allowed to account for thermal zones that combine different spaces for example an open office next to a lobby and corridor area all within the core of a building Next enter the proposed values for lighting and receptacle power density or select the Use Baseline Value checkbox The proposed value entries are given for convenience so that the user can compare the proposed and baseline values They are not used in any calculations To finish click OK and the tool creates a new line in the spreadshe
13. at rated conditions in H O T Fan The combined efficiency of the fan and motor at rated conditions Where the above values are known the fan power can be calculated easily However if the above values are not available some assumptions are necessary When the rated supply airflow is not known a typical value of 350 CFM ton can be used and the airflow 15 calculated to be 13 Qt rated CFM 12 350 7 h ton where 0 ratea is the AHRI rated capacity of the proposed unit in kBtu h To determine the total static pressure of the system at rated conditions it is necessary to know both the internal and external static pressures at rated conditions Internal static at rated conditions SPinternal rated should include the packaged unit with wet coil and no filters If not entered by the user from manufacturer s data it is assumed to be 1 00 in H O This value has been estimated based on data from several manufacturers packaged unit catalogs Energy Model Input Pre Processor User s Guide 14 The external static at rated conditions is determined by referencing ANSI AHRI Standard 340 360 According to the standard the minimum external static pressure used to rate equipment efficiency SPoxternal rated Varies according to rated capacity in the following manner Table 2 Minimum External Static Pressure for EER Testing Rated Capacity Minimum External Btu hr Static Pressure in H O This
14. baseline system calculator is very similar to the proposed system calculator in that it determines fan power kW CFM for supply return and exhaust and it calculates compressor COP and EIR To begin click Add System and the following form appears Energy Model Input Pre Processor User s Guide 16 Baseline System Inputs Baseline System System Name System System Notes Notes 2 PTHP Retrofit 3 PSZ AC System type should be based on ASHRAE 90 1 2007 4 PSZ HP Appendix guidelines located in Table G3 1 1 Select System Type 5 Pkg VAV w reheat Baseline System Type Selector 6 Pkg VAV w PFP Boxes 7 wj reheat Electric None Heating type should be the same as the proposed system Fossil Fuel Select Heating Type Total Cooling Load 218000 Btu h Enter auto sized cooling load from model induding 15 oversizing Supply Airflow 10000 CFM Enter auto sized supply CFM from model Enter the amount of propsed room exhaust located in the Exhaust Airflow 2000 baseline zone Do not include system exhaust at the unit Enter the ratio of supply fan power to total fan power from the Supply Fan Ratio 0 650 Return Fan Ratio 0 200 Enter the ratio of return fan power to total fan power from the proposed design Enter the ratio of exhaust fan power to total fan power from Exhaust Fan Ratio 0 150 ike proposed Go to Pressure Drop Ad
15. edinticnecaFiE deniddd dnt arro Dead addi datu drin ical ag 5 4 1 LIGHTING POWER amp OCCUPANT DENSITY 5 4 2 DOMESTIC HOT WATER CALCULATOR 5 2 eorura aano aaa En aab a FER YPEYREREERERERERYRIRRERRERERERKR KS 7 421 Tank UA Value 7 422 Hot Water Use 9 4 2 8 Input Power amp Storage Capacity Estimator esses enne 9 4 3 COOLING TOWER FAN EFACIENCY CALCULATOR a 242522252222222222222472 A72cA AA 10 431 Proposed C896 La 11 432 Baseline ase orit ag ose 11 44 PROPOSED SYSTEM FAN POWER amp EFFICIENCY 11 4 4 1 Fan Power 12 4 42 Compressor COP Calculation esses sies enne 13 4 5 BASELINE SYSTEM FAN POWER amp EFFICIENCY CALCULATOR cccccccceceeeceeeeeeeeeeeeeeeeeeeeeeeeess 16 4 5 1 Fan Power CalCulations ccccccsseccccceccceensssececececeesssasasesecessesasasesesecseseeauaceseseceeceneaussssececeers 17 4 5 2 Compressor COP Calculation 19 4 6 SCHEDULE CREATOR AND
16. et for the new zone To edit the zone values the user can directly change the cell data or use the Edit Zone button to bring up the same form and edit values from there To delete a zone click Delete Zone and the select the zone to be deleted Additional Notes Energy Model Input Pre Processor User s Guide 6 e The first zone in the spreadsheet is locked so that subsequent zones be copied from it Schedules When using default baseline values from sources such as ASHRAE 90 1 and Title 24 be sure to use the corresponding fraction use schedules from these sources as well ASHRAE 90 1 schedules can be found in the Schedule Lookup tab and Title 24 schedules can be found in the 2005 California ACM Manual 4 2 DOMESTIC HOT WATER CALCULATOR Intent Energy modelers often struggle to translate code specifications and manufacturer s data into energy model inputs for domestic hot water The purpose of this spreadsheet calculator is to bridge that gap and determine ASHRAE 90 1 2007 baseline hot water heater full flow rate efficiency and tank heat loss and calculate these same values using manufacturer s data for proposed water heaters The calculators in this spreadsheet can also be used to estimate water heater performance when design data is unavailable Directions When all design data is available the calculations are simple Enter the required design data for the proposed system as indicated by dark blue cells includi
17. external static pressure is added to the internal static pressure to get the total static pressure at rated conditions 14 SP rated SPinternal rated SPexternal rated When unavailable combined fan and motor efficiency is assumed to be 0 650 This value is taken from ASHRAE 90 1 2007 Table 6 5 3 1 1A where the adjustment to fan bhp A is defined as 15 A bhp x PD 4 131 From Equation 12 we know that 16 Due CFM x PD X 6 356 2 0 X Nfan Setting the two previous equations equal to each other and simplifying we can determine that for pressure drop adjustments in ASHRAE 90 1 2007 combined fan and motor efficiency is assumed to be 17 _ 4 131 _ Iran 6356 With all of the variables in determined the adjusted EER can now be calculated 18 Energy Model Input Pre Processor User s Guide 15 Qt rated ran rated 0 t rated EER Pran rated where The adjusted Energy Efficiency Ratio for calculation purposes W h EER The rated Energy Efficiency Ratio Btu W h Qran rated rated X 2 545 The fan heat at rated conditions kBtu h Pran rated BH Pougpty X 0 7457 51 The fan power at rated conditions KW Compressor COP is then calculated as follows 19 PS 3 413 2 The energy input ratio EIR is the inverse of the calculated COP 4 5 BASELINE SYSTEM FAN POWER amp EFFICIENCY CALCULATOR The
18. ing type and conditioned area and estimates the number of occupants and hot water use per occupant per day to get a total baseline usage per day The user can then de rate that baseline by a percentage to estimate the proposed usage The occupant density for each building type is taken from the 2005 California ACM and hot water use is taken from COMNET Appendix B Table 5 This calculation is a rough estimate and should only be used when no design data is available 4 2 3 Input Power amp Storage Capacity Estimator The input power and storage capacity estimator uses building type and area to calculate peak hot water use and storage capacity All calculated loads assume a 90 F differential between inlet and outlet water temperatures which is based on typical design values of 50 F inlet and 140 F outlet Additionally a 20 safety factor is applied to all calculations as evidenced by the first number in the equation being 1 2 The calculation of input power varies depending on whether the proposed system is an instantaneous system or storage system Instantaneous Water Heater The instantaneous water heater calculation assumes no storage is used and the peak instantaneous load is required to be met by the water heater Peak load is determined by calculating the total number of hot water fixture units in the building and converting that to a hot water flow rate using the modified Hunter curve Fixture unit numbers are Energy Model I
19. itions and COP for specific conditions in the simulation are calculated from rated conditions based on part load curves There are two ways to calculate COP from EER in this tool The simplest way is to use EER net cooling capacity and gross cooling capacity This way we can solve for supply fan power and total input power using equation 8 and plug those values into equation 10 Combining and simplifying these two equations results in the following equation for COP 11 d 7 Btu Pops Gross Cooling Capacity 7 3 413 2 x Rated Cooling Gross Cooling 22 Energy Model Input Pre Processor User s Guide 13 However if one of these three values is unknown this equation cannot be used directly In many cases the unknown value is gross cooling capacity at rated conditions In this case it is necessary to calculate supply fan power which is directly related to supply fan heat If supply fan heat is known then the gross capacity can be calculated by adding supply fan heat to net cooling capacity to get gross cooling capacity and equation 11 can be used If supply fan heat or power at rated conditions is not known then the calculations become more complex The supply fan power at rated conditions can be calculated in the following manner 12 p where rated The supply fan power at rated conditions bhp CFM ated The supply airflow at rated conditions CFM SP rated The total static pressure
20. justments Input You must review Pressure Drop Adjustments before saving the system Click on the Go to e Pressure Drop Adjustments Input button Figure 3 Baseline system input form inputs on the form are required except if systems 7 or 8 are selected cooling load is not required If the 90 1 baseline system type is unknown the user can click on the Baseline System Type Selector and determine which baseline system is appropriate 4 5 1 Fan Power Calculations The fan power calculations require the user to enter supply and exhaust CFM as well as supply return and exhaust fan ratios Return CFM is calculated by subtracting exhaust from supply Fan power ratios are used to determine how much of the allotted baseline fan power is used for each system These ratios must be equal to the ratios of fan power in the proposed system To calculate the ratios for the proposed system sum up all fan power for each type supply return and exhaust and divide the sum by the total fan power equal to the sum of these three sums In the event that a proposed system fan serves Energy Model Input Pre Processor User s Guide 17 thermal blocks covered by different baseline systems the fan power must be divided between the baseline systems in proportion to proposed CFM After all inputs have been determined the allotted baseline fan power can be calculated This calculation is done per ASHRAE 90 1 2007 section G3 1 2 9 Adjustments t
21. m calculations as outlined in equations 12 through 19 except that instead of manufacturer s data the values listed as assumptions in the proposed system description are used and the baseline EER is determined from the rated capacity and ASHRAE 90 1 2007 Tables 6 8 1A amp B The assumptions made are 1 Combined fan motor efficiency fan of 0 650 2 Rated airflow of 350 CFM ton So if we return to equations 18 and 19 and combine them we get 20 COP Qi rated Q fan rated 3 413 Suse Pran rated We also know that 21 P _ rated fan rated 5 745 3 4132 So if we substitute for Pran ratea and simplify then we find that 22 Qt rated ran rated Q 3 413 PER m ran rated COP If we take equation 12 for fan power and convert from brake horsepower to kBtu h then we get 23 Q CFM atea x SP rated rated 5 an ww fan rate 249608021 X Now if we substitute the two assumptions from above 350 CFM ton and 0 65 combined fan and motor efficiency then we get 24 Qei rated x 350 SP rated Q 12 0 00000 Qtiratea X SPrratea fen vated 49 6 seam 20 1 x 0 65 55 615 in H50 Energy Model Input Pre Processor User s Guide 19 Now if we substitute for Qran 4 4 in equation 22 we get 25 Qi rated x SP rated SP rated M 755 615 in H 0 _ 1 55 615 in H C tro 2 413 Qi rated
22. ng the schedule to the right then enter the auto sized values for the baseline system and the spreadsheet calculates the efficiencies tank UA value and full flow rate GPMs The tank UA value can be difficult to find on manufacturer s cutsheets so a calculator is provided to help the user determine an appropriate value 4 2 1 Tank UA Value Calculator Tank UA Value is the rate at which heat is lost from the stored hot water as a function of the temperature differential between the water and the air surrounding the tank The units of Tank UA are Btu h F To use the UA value calculator the user will need to have one of three sets of design values for the proposed system Energy Factor amp Recovery Efficiency Standby Loss or Tank Diameter amp R value The calculator contains links to the AH RI database of residential and commercial water heater test results so if the proposed model number is available this data can be looked up If this data is unavailable the user may estimate values based on the typical values listed at the bottom of the calculator A good sanity check is that the UA value of the proposed tank is less than that of the baseline Energy Factor Recovery Efficiency The energy factor recovery efficiency calculation uses the following equation to determine tank UA Energy Model Input Pre Processor User s Guide 7 1 LT U Atank E RE 1 ME c s 41094 REX Pm where UAtank The hot water storage tank UA val
23. nput Pre Processor User s Guide 9 taken from the 2007 ASHRAE Handbook of Applications Chapter 49 Table 16 and the modified Hunter curve can be found among other places in the 2003 International Plumbing Code Table E103 3 Once the flow rate is determined the instantaneous load is calculated using the following equation 6 Btu h gal P 12 8 33 l x 60 x GPM x 90 F Storage Type Water Heater Storage type water heaters utilize stored hot water to shave peak loads and reduce required input power significantly relative to instantaneous water heaters Calculations for this type of system are taken from the 2007 ASHRAE Handbook of Applications Chapter 49 pages 49 15 through 49 19 Figures 16 through 23 of the Handbook give average values for required recovery rates in GPH person and corresponding storage capacity in gal person Numbers of occupants is calculated based on building area and the required recovery flow rate and storage capacity are determined by multiplying the number of occupants by the factors taken from the Handbook Input power is then calculated from recovery flow rate GPH 7 Btu h gal P 1 2 x 8 33 x GPH x 90 F Thermal Efficiency Once storage capacity and input power are determined the input power is adjusted for thermal efficiency based on the type of fuel and whether the user chooses a standard or high efficiency water heater The following values are used for thermal
24. o fan power are required to be reviewed When the Go To Pressure Drop Adjustments button is clicked the following form appears ASHRAE 90 1 2007 Table 6 5 3 1 1B Pressure Drop Adjustments Type of Device Allowable Adjustment Design Airflow at Device Check off each device found in the system Input Allowable additional pressure drop for Enter the portion of airflow that flows through variables to the right of each device as necessary each device Where input boxes are the device at PROPOSED design conditions available enter PD at proposed This could be less than 100 of the total design condition airflow but should not be more than 100 Fully ducted return and or exhaust air system s 0 50 in w c Return and or exhaust airflow control devices 0 50 in w c Exhaust filters scrubbers or other exhaust treatment 0 in w c filters 9 12 0 50 in w c MERV filters 13 15 0 90 inw c 16 or electronically enhanced filters 0 in w c w clean filter Carbon or other gas phase air cleaner 0 in w c Heat Recovery Device 0 in w c Evaporative humidifier cooler in series with cooling coil 0 in w c Sound Attenuation Section 0 15 in w c Fume Hood Exhaust Exception 1 0 in w c TABLE 6 5 3 1 1B Fan Power Limitation Pressure Drop Adjustment Device Adjustment Credits Fully ducted retum and or exhaust atr systems 0 5 in w e Return and or exhaust ai
25. rflow control devices 0 5 in we Exhaust filters scrubbers or other exhaust treatment The pressure drop of device calculated at fan system design condition Particulate Filtration Credit MERV 9 through 12 0 5 in w c Particulate Filtration Credit MERV 13 through 15 0 9 in w c Particulate Filtration Credit MERV 16 and greater Pressure drop calculated at 25 clean filter pressure drop at fin system and electronically enhanced filters design condition Carbon and other gas phase air cleaners Clean filter pressure drop at fan system design condition Heat recovery device Pressure drop of device at fan system design condition Evaporative humidifien cooler in series with another cooling coil Pressure drop of device at fan system design condition Sound Attenuation Section 0 15 in we Deductions Fume Hood Exhaust Exception A lt 1 0 in w c required if 6 5 3 1 1 Exception c is taken Figure 4 Pressure drop adjustments input form applicable adjustment options should be checked and the appropriate airflow should be entered Airflow is a required input because the adjustment calculation only Energy Model Input Pre Processor User s Guide 18 accounts for the airflow passing through the device not the total supply airflow The applicable section of ASHRAE 90 1 2007 is shown for reference 4 5 2 Compressor COP Calculation Compressor COP for baseline systems can be calculated in a similar manner to the proposed syste
26. ual 8760 schedules are available for EnergyPlus Many more options are available for eQuest 4 6 1 eQuest Schedule Output eQuest schedules may be created for a single day week or year When the type of schedule is determined from the form the appropriate input table will appear Theuser can then enter the values Depending on the schedule type limits are placed on the acceptable values the user can enter in the table Once data entry is complete the user clicks Export Schedule and selects the directory to which they would like to save the Energy Model Input Pre Processor User s Guide 21 schedule The schedule is saved as an inp file which the user can import using the File Import File command in eQuest When a weekly schedule is made in the inp file the following assumptions are made for the heating and cooling design day schedules Table 3 Design Day Schedule Assumption Weekly Design Day Schedule Type Assumption Weekly 5 2 Weekday Weekly 5 1 1 Weekday Weekly 7 day Monday Annual 8760 Monday The design day schedules can only be changed manually inside the input file See the eQuest documentation for instructions on how to do this 4 6 2 EnergyPlus Schedule Output EnergyPlus schedules are currently limited to Annual 8760 schedules only The schedules are exported as Schedule File type schedules where an file is created with the name and type of the schedule and a csv file
27. ue Btu h F EF The energy factor of the water heater determined by testing RE The recovery efficiency of the water heater determined by testing P The input power of the water heater Btu h This equation is taken from an EERE document Equation D 2 14 found at http www 1 eere energy gov buildings appliance standards residential pdfs D 2 pdf Standby Loss The standby loss conversion is calculated as follows 2 UA nk SL X 70 F where SL The standby loss of the storage tank determined by testing 70 F The standard differential temperature between the tank water and ambient air used in testing R Value Diameter V olume When the R value of the tank insulation is known the tank UA can be calculated by using the storage volume and tank diameter to calculate surface area 3 D A base T 4 Vstorage 7 48 25 surface 2 A base ase 5 Asurface UA tank R Energy Model Input Pre Processor User s Guide 8 where Abase The area of the base of a cylindrical tank ft D The diameter of a cylindrical tank ft Asur face The total surface area of a cylindrical tank ft Vstorage The tank storage volume gal R The R value of the tank insulation h F ft Btu When design data is not available proposed values may be estimated using the Hot Water Use Estimator and Input Power amp Storage Capacity Estimator 4 2 2 Hot Water Use Estimator The hot water use estimator takes the build
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